Geoffrey

I give up.

PS. was supposed to say 993tt Porsche cars.


[edit] maybe one more thought
The thing that you guys are missing is that the function of the compressor wheel determines the airflow and pressure ratio within the effeciency island, not the turbine. The turbine only powers the compressor, that is all it does. It does not determine compressor efficency per se, and only effects the compressor speed, and spool time. A k24 compressor will flow more air than a k16 compressor there is no question about that. The k16 hybrids use compressors that flow more air than a k24 compressor. Kevin's stage 1 turbo is a GT1 turbo which uses a k24 compressor. Kevin's line of hybrids use compressor wheels from stage 1 small (k24) to stage 5 large (about the size of a K27) and I can tell you that a k27 compressor wheel flows more air than a k24.

The reason a k16 falls of is that as RPM increases, it falls outside its efficency island and cannot flow air nor maintain boost. A k24 does this also, somewhere around 525-550hp. So by replacing the k16 compressor wheel with a larger wheel that can maintain airflow, pressure ratio within its efficiency island, you are solving the problem. The larger compressor wheel is natrually heavier than the k16 so the turbine has more mass to get moving, and more resistance because of the "bite" of the compressor wheel, but it is minimal so the turbo retains the low lag of a stock k16.

The k24 turbine is larger, so it takes more energy to get the turbo moving and get the compressor spinning. This is why the lag issues exist with the k24.

FWIW, the massive single turbo on my engine has a turbine SMALLER than a k27!

K24madness

The one thing that everyone seem to be ignoring is the upside of the larger K24 hot side is that it give less exhaust back pressure than the K16 hot side. Even though the hybrids have equal to or better than k24 cold sides the benifit of reduced exhaust back pressure of the k24's can't be ignored.

Kevin

K24madness;

What kind of backpressure are we talking about... Most people dump there cats and gut the mufflers anyway... Believe me, that is where my turbine housing mods come into play... The last resort is to CLIP the wheel, it will free up the turbine side, but you'll take a hit on lag reduction.. It is not an issue...

K24madness

Kevin could you give a breakdown of the stages for the hybrids and what stage you recommend for what boost pressure/application. THIA

gooseNSJ4

What about the rest of us that do not dump the cats because of the State inspection issues, most states if not all require them and taking them of and putting them back on could become a headache.
So if you take this under consideration the back-pressure that K24maddness is talking about is something that should be considered.

Not trying to be argumentative just trying to gain some sanity, so one can get some sleep better medicine!

Kevin

Goose;

We are seeing sustained 1.3 bars on the 996TT.. with the Stage 2 setup.. There is not an issue with the K16's.. Ruf is using the K16 platform, I don't think that Bill is having issues with his Ruf turbo's, and Rolands 200 MPH Ruf K16's.. To me it's all hogwash.. Looks at John's post with his new Stage 4's AND HIS engine is a 3.8 ltr... It is not an issue..